Holding brake for power transmission



y 1949. R. M. SMITH 2,475,997

HOLDING BRAKE FOR PO WER TRANSMISSION Filed Sept. 29, 1947 2 Sheets-Sheet 1 IN VEN TOR.

BY/fo ber/Zjm/ a; a 2 W,

ATTORNEY July 12, 1949. R. M. SMITH 2,475,997

HOLDING BRAKE FOR POWER TRANSMISSION Filed Sept. 29, 1947 2 Sheets-Sheet 2 ll 20 Q I! INVENTOR.

Reaper/ll ATTORNEY UNITED STATES PATENT osrica HOLDING BRAKE FOB POWER TRANSMISSION Roger M. Smith, Phoenix, Aria, asaignor to caterpillar Tractor 00., San Leandro, Call! a corporation of California Application September 29, 1941, Serial'No. 776,825

'1 Claims. (01.192-4) This invention relates to a brake employed with drive shaft i1 is connected with a suitable power a power transmission mechanism to prevent rotake-oi! shaft (not shown) of an internal comtation of the transmission driven shaft except bustion engine or other prime mover of the road when it is intentionally connected through the grading machine. As the bevel gears l2 and I3 transmission with the drive shaft. 5 are constantly driven in opposite directions, con- The invention has been employed in connection motion of either one or the other of these gears with road grading machinery wherein various with the driven shaft l'l will be effective to imadjustments of the machine parts are effected by part rotary movement to the driven shaft selecpower taken from the prime mover of the matively in opposite directions. Each of the gears chine and controlled by individual manually conlo i2 and i3 is provided with a toothed clutch face trolled transmissions. The following disclosure as indicated at I8 and i8 respectively and a clutch will, therefore, be directed to the invention in shifting collar 20 is slidably but non-rotatably connection with such use though its adapt-ability carried by the driven shaft ll through the meto various other uses will be apparent as the dedium of a splined connection 2 i-as also shown in scription proceeds. Fig. 2. The clutch collar is provided with toothed It is an object of the invention to provide an clutch faces 22 and 23 for engagement with the improved holding means for use with a power clutch faces l8 and i9 respectively of the gears transmission mechanism wherein braking of the i2 and I3. transmission driven shaft is automatically ef- In order to effect shifting of the clutch collar fected inneutral position but wherein the shaft is longitudinally of the shaft ll selectively to encapable of rotation in either of two driving pogage its clutch faces with the gears l2 and l3, s. sitions. Further and more specific objects and shifting fork 24 is connected'as by a pin 25 with advantages of the invention as well as the details a shifting rod 26 extending through and slidable of its construction are made apparent in the folwith relation to the transmission housing. A lowing specification wherein reference is made 25 manually controlled lever 21 disposed exteriorly to the accompanying drawings. of the housing is arranged to be rocked about a In the drawings: pivotal connection 28 and is connected as by a Fig. 1 is a central vertical section through a pin 23 with the shifting rod 23. Springs 33 and transmission havinga braking mechanism em- 3|, interposed between the inner walls of the bodying the present invention;. 3 housing and the shifting fork 24, normally main- Fig. 2 is an enlarged sectional view taken on tain the shifting fork in a central or neutral poline 11-11 of Fig. 1; and sition with relation to the shifting collar 20 so Fig. 3 is a fragmentary view similar to Fig. 1 that neither of the gears l2 or l3 are connected but illustrating a different position of the transwith the driven shaft ll. Swinging movement mission parts and braking mechanism. manually imparted to the lever 21, however, in In Figs. 1 and 3 of the drawings, a transmission either direction will compress one of the springs housing of conventional design is illustrated at 30 or 3| and effect a driving connection between Ill as containing a driven shaft l'i suitably jourthe shifting collar and one of the gears II or l3. nailed for rotation in the housing and extending Ordinarily, the shifting fork 24 is provided with outwardly through one side of the housing as a pair of tines as indicated at 32 and 33 in Fig. 2, shown where it will in practice be connected with the lower ends of which would engage the shiftsome part to be controlled. Such part, for exing collar 20 by reception in an annular groove 34 ample, may be the scraper blade on a road gradformed therein. In accordance with the present ing implement, and mechanism will be employed invention, however, the tines of the shifting fork for raising of the blade upon rotation of the impart shifting movementtothe collar 20 through driven shaft in one direction and lowering of the an intermediate member in the form of a twoblade upon its rotation in the opposite direction. part yoke generally indicated at 35. The yoke Rotary movement is imparted to the driven shaft 35 is made up of two separate inverted U-shaped ll through either one of a pair of bevel gears l2 members, one of which is shown at 36 in Fig. 2 and I3 normally freely rotatable on the shaft and 60 and each of which is provided with a pair of outconstantly driven in opposite directions by a wardly extending ears 31 adapted to be received meshing bevel gear Il The gear I is carried in the lower bifurcated ends 33 of the shifting on a stub shaft l5 which is connected as by worm fork tines 32 and 33. Each of the yoke members gearing occupying the position indicated in 36 is also provided wih an upwardly extending lug dotted lines at IS with a drive shaft H. The 40 and these lugs are received in a notch 4i When the transmission is in neutral position as" illustrated in Fig. 1, the springs 42 tend to urge the yoke parts 36 outwardly or away from each other and into contact with the side walls of the g annular groove 36 in the shifting collar 20. This 7 contact effects a braking action against the shifting collar 26 and as the shifting collar is splined v to the shaft ii it prevents the rotation of this shaft which otherwise frequently occurs as a.

result of vibration and other conditions which are encountered during the operation of road grading machinery or the like. When the transmission; is shifted as by moving the lever 21 to the left as indicated in Fig. 3 to effect movement of the shifting collar-26 to the left for engagement of its clutch face with the clutch face on the gear II, the lower bifurcated ends 36 of the shifting fork 24 engage the ears 31 of one of the yoke members 36, in this case the right hand yoke member 1 as viewed in Fig. 3. Consequently, the springs 62 are compressed so that the right hand member 36 is moved out of its breaking engagement with the shifting collar and the entire yoke including both of the members 36 is moved in a direc- 1 tion longitudinally of the shaft Ii to slide the shifting collar thereon in the direction desired.

. The braking action between the yoke members and the shifting collar is in this manner materially reduced and is not sufilcient to interfere materially with the drive of the shaft l I through the transmission mechanism described. Likewise, movement of the shifting fork 21 in the opposite direction from its neutral position will effect release of the brake and shifting of the collar 26 for engagement with the opposite bevel 1 ear II. On release of the manual control lever 21 from either ofits shifted positions, the springs 36 and 3| return it to and retain it in its normal or neutral position and the springs 42 between the yoke-like brake members are automatically effective to spread the brake members apart and into braking engagement with the shifting collar 20.

I claim:

1. In a power transmission comprising a driven shaft, a pair of gears rotatable thereon, and a grooved shifting collar. rotatable with and slidable on the shaft to effect a driving connection with either of said gears, a shifting fork for sliding the collar and friction brake means interposed between the fork and the sides of the groove in the collar to prevent rotation of the driven shaft. except when the collar is in driving position.

2. In a power transmission comprising a driven shaft, a pair of gears rotatable thereon, and a shifting collar rotatable with and slidable on the shaft to effect a driving connection with either of said gears, said collar having an annular groove therein, a shifting fork for sliding the collar, and a connection between the fork and the collar comprising a pair of yokes disposed in the collar me of this patent:

groove, springs between said yokes for urging of the groove, and a shifting fork having bifurcated tines embracing said brake members to compress said springs and effect sliding of the collar in either direction on the shaft.

4. In a power transmission which includes a driven shaft and a sliding collar thereon for selectively connecting the shaft with either one of two driving gears. said collar having an annular groove, a pair of brake members disposed in the groove. springs between said brake members to urge them into braking contact with the sides of the groove. and a shifting fork having bifurcated tines embracing said brake members to com ress said springs and effect sliding of the collar in either direction of the shaft, and a connection between the fork and the brake members to hold the brake members against rotation with the collar.

5. In a shifting device for transmissions and the like which includes a grooved shifting collar and a fork associated with the groove for shifting the collar, brake means comprising a resilient assembly for imposing friction on the sides of the groove, and a connection between the fork and the brake means through which shifting movement may be imparted to the collar.

6. In a shifting device for transmissions and the like which includes a grooved shifting collar and a fork associated with the groove for shifting the collar, a pair of brake members engageable with opposite sides of the groove, resilient means urging said members into frictional contact with the sides of the groove, and a connection between the fork and the brake members for imparting shifting movement to the collar.

. 7. In a shifting device for transmissions and the like which'includes a grooved shifting collar and afork associated with the groove for shifting the collar, a pair of brake members engageable with opposite sides of the groove, resilient means urging said members into frictional contact with the sides of the groove, and a connection between the fork and the brake members for imparting shifting movement to the collar, said connection embracing both brake members to eflect compression of shifting of the collar.

REFERENCES CITED The following ref rences 2,208,518 R088 -i. July 16, 1940 are of record in the 

